1. Field of the Invention
The invention relates to methods to increase the paint adhesion of an article made from compatibilized polyphenylene ether-polyamide resin blends.
The invention also relates to the compositions and articles, e.g., automotive components, made from the compositions.
2. Brief Description of the Related Art
Poly(phenylene ether) resins (referred to hereafter as “PPE”) are commercially attractive materials because of their unique combination of physical, chemical, and electrical properties. Furthermore, the combination of these resins with polyamide resins into compatibilized blends results in additional overall properties such as chemical resistance, high strength, and high flow. Examples of such compatibilized blends can be found in U.S. Pat. No. 4,315,086 (Ueno, et al); U.S. Pat. No. 4,659,760 (van der Meer); and U.S. Pat. No. 4,732,938 (Grant, et al).
The physical properties of PPE/polyamide blends make them attractive for a variety of end-use articles in the automotive market, especially for various painted exterior components. However, when these compositions are to be utilized in automotive applications it is generally desirable to improve their impact properties, especially when used as exterior automotive body panels, bumpers, and the like, by adding impact modifiers.
Some of the more desirable applications, for example, automotive fenders require the molded plastic parts affixed to the automobile frame to go through high temperature ovens used to cure the anti-corrosion coating that has been applied to the metal panels. High temperature cures are especially important in the so-called “E-coating” process, in which an epoxy coating is applied to the metal parts and then cured prior to electrostatic painting, In electrostatic painting, a uniform coating of paint is established as the result of an electrical attraction between the metal part and positively charged paint particles. The ovens typically reach temperatures of about 165° C. to about 230° C. or higher for periods of 10 to 50 minutes or longer. These temperatures often cause low molecular weight ingredients or reaction products present in the polyphenylene ether polyamide compositions to migrate to the surface, leading to the formation of a film on the surface of the respective article. Such films are undesirable and often give rise to paint adhesion problems. The ability to withstand the time and temperature of the ovens without distortion limits the success of many plastic resins. Moreover, paint adhesion issues with plastic panels after passing through the ovens has also limited their acceptance. It is therefore apparent that a need continues to exist for improved thermoplastic compositions and method to improve paint adhesion on such compositions for painted automotive components.